1. Field of the Invention
The present invention relates generally to tire pressure monitoring systems and more particularly, to a wireless tire pressure monitoring system for use in a towing vehicle.
2. Description of the Related Art
A wireless tire pressure monitoring system outputs measured tire pressure data of each vehicle wheel in the form of a packet by means of wireless communication transmission. The packet contains measured data of every vehicle wheel and the corresponding identification code. When the receiving antenna received this measured data and identification code, the monitoring main unit in the driver's cab identifies the wheel subject to the identification code so that the driver can monitor the tire pressure of every vehicle wheel. More particularly, the use of a wireless tire pressure monitoring system in a towing vehicle or the like where the wheels operate under a high load condition effectively monitors the tire pressure status of every wheel, maintaining the service life and assuring driving safety.
FIGS. 5 and 6 illustrate the arrangement of a wireless tire pressure monitoring system 1 in a towing vehicle 2 according to the prior art. As illustrated, the monitoring main unit 10 in the driver's cab at the truck-tractor 21 is electrically connected to a receiving antenna 12 at the bottom side of the platform 2, and a tire pressure sensor 13 is respectively installed in the air nozzle of each wheel 23 of the truck-tractor 21 and each wheel 24 of the platform 22. Each tire pressure sensor 13 sends the measured data in the form of a packet to the receiving antenna 12 wirelessly. When received one packet and processed out the contained data, the monitoring main unit 10 checks whether there is a built-in address data corresponding to the identification code in the contained data. When the identification code matched, the monitoring main unit 10 displays the tire pressure status of the corresponding wheel.
A towing vehicle usually carries a heavy load that contains a big number of articles. Before transportation, the load to be carried is loaded on the platform, and then the platform is coupled to a truck-tractor for carrying by the truck-tractor to the destination. When arrived at the destination, the platform with the load is disconnected from the truck-tractor, and then the truck-track is driven to transport another platform that has another load loaded thereon. When the aforesaid prior art wireless tire pressure monitoring system 1 is used in a towing vehicle and when the platform 22 is disconnected from the truck-tractor 21 and coupled with another platform, the monitoring main unit 10 needs to set the identification code of every wheel 24 of the newly attached platform 22 into corresponding specific address data so that the monitoring main unit 10 can identify the packet produced by the tire pressure sensor 13 at each wheel 24 of the newly attached platform 22 for accurate indication. In other words, each time the towing vehicle changes the platform, the wireless tire pressure monitoring system 1 completes the identification setting of every wheel of the newly attached platform before delivery of the load. This identification setting procedure is complicated. In case of a human error, the monitoring main unit will be unable to monitor all the wheels accurately, and any false indication upon an abnormality of the wheels may threaten the driving safety.